1. Field of the Invention
This invention relates to input/output port switchers for personal computers (PC), and more particularly, to a dynamic printer-port switcher (DPS) which allows a PC to be selectively connected under software control to one of a plurality of peripheral devices, such as printers, PC cameras, and other various peripheral devices.
2. Description of Related Art
A PC is customarily provided with a printer port (i.e., the parallel port) that allows the PC to be connected to a printer. In addition, the printer port allows the PC to be connected to various other peripheral devices, such as a PC camera, a scanner, an external CD-ROM drive, an external hard disk drive, and so on. However, since one PC is typically provided with only one printer port, the PC can be connected to these peripheral devices only one at a time. When the user wishes to connect the PC to another peripheral device, he/she should first disconnect the current peripheral device from the printer port and then connect the desired one to the printer port. This work is quite inconvenient and laborious for the user to do. It also causes wear to the connectors of these peripheral devices.
One solution to the foregoing problem is to provide each of the peripheral devices with a dedicated connecting port on the PC. However, since the dedicated connecting ports are provided on additional expansion cards, they will occupy more expansion slots in the PC. Therefore, although this solution may be suitable for desktop computers which are spacious enough to provide enough expansion slots, it is not suitable for notebook computers. Moreover, the provision of these additional expansion cards is quite costly to realize.
A cheap solution is to connect all of the peripheral devices via a switcher to the printer port, which allows the user to selectively switch the connection between the PC and one of the peripheral devices.
FIG. 1 is a schematic block diagram used to depict the application of a conventional printer-port switcher 100 for selectively connecting a PC 110 to either one of two peripheral devices, such as a printer 120 and a PC camera 130. The printer-port switcher 100 has one port connected to the printer port 110a on the PC 110 and the other two ports connected respectively to the printer 120 and the PC camera 130. Only one of the printer 120 and the PC camera 130 can be connected via the printer-port switcher 100 to the printer port 110a at a time. The user can do this simply by manually flipping a switch (not shown) on the printer-port switcher 100. However, the manual operation is quite inconvenient and laborious to do.
There is a conventional electronic type of switcher which is specifically devised for a PC to be selectively connected to a number of printers. The destination printer is software-controllable by the user. This type of switcher, however, is only uni-directional, which means that the data can be transferred only from the PC to the selected one of the printers, and not in the reverse direction. Therefore, it can not be used to connect those types of peripheral devices that involve data input to the PC, such as PC cameras, scanners, external CD-ROM drives, and external hard disk drives. There exists, therefore, a need for a dynamic printer-port switcher that can transfer data between a PC and a plurality of peripheral devices in both directions.